In the discussion of the background that follows, reference is made to certain structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicant expressly reserves the right to demonstrate that such structures and/or methods do not qualify as prior art.
Vertical shaft impact crushers (VSI-crushers) are used in many applications for crushing hard material, like rocks, ore etc. WO 2004/020103 describes a VSI-crusher including a housing and a horizontal rotor located inside the housing. A first material flow is fed to the rotor via an opening in the top thereof. The first material flow is accelerated by the rotor and is ejected towards the wall of the housing. A second material flow is fed outside the rotor, for example, between the rotor and the housing. This second material flow is hit by the first material flow ejected by the rotor. Thus, the first and second material flows are crushed against each other just outside the rotor.
The second material flow is directed into the first material flow via a hillside of material which has been built up against an upper surface of a cavity ring, which separates a distributing wall section from an impact wall section, and one or more collection plates that are located on the upper surface of the cavity ring. The second material flow causes wear on the cavity ring and the collection plates, resulting in frequent need for time consuming and cumbersome maintenance work.